AB1459 IGG4-RELATED DISEASE: 2010-2022 CASE REVISION AND PERFORMANCE OF DIAGNOSTIC CRITERIA
Authors: P. Martinez Calabuig, J. J. Fragío Gil, A. Rueda, L. Salvador Maicas, R. González Mazarío, L. Abenza Barbera, M. C. Sabater Abad, A. Sierra Rivera, I. Castelló Miralles, J. J. Lerma, C. Molina Almela, M. D. Pastor Cubillo, C. Campos
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> IgG4 immunoglobulin-related disease (IgG4-RD) is a rare, systemic immune-mediated fibro-inflammatory process with unclear etiology and pathophysiology. Can affect multiple organs that encompass common pathophysiological, serological and clinical characteristics. <h3>Objectives</h3> To describe the heterogeneity of the clinical presentation, evolution, and treatment of patients diagnosed with IgG4-RD and compare the performance of the last two IgG4-RD classification and diagnostic criteria. <h3>Methods</h3> Single-center retrospective study in which patients with a possible diagnosis of IgG4-RD from various hospital departments are studied from January 2010 to August 2022. Some exclusion criteria were applied (patients with clinical manifestations attributable to other diseases were excluded) and to those who remained with a suspected diagnosis of IgG4-RD, the Umehara-Okazaki 2011 and ACR/EULAR 2019 criteria were applied. <h3>Results</h3> 182 patients with elevated IgG4 and/or a suspected diagnosis of IgG4-RD were collected. Finally, after exclusion criteria, 22 possible patients with IgG4-RD remained (Table 1). The diagnostic criteria proposed by Umehara and Okazaki in 2011 are applied to these patients, including a total of 13 patients, with a mean age of 60 years, 57% women; 5 being classified with definitive disease, 3 as probable disease and 5 as possible disease. Finally, we applied the ACR/EULAR 2019 classification criteria to those patients too, establishing diagnosis in 7 patients. The mean age was 57 years, 71% were women with a mean follow-up of 5.3 years; 85.71% of the patients had elevated IgG4, with mean levels of 176.3 mg/dL. Retroperitoneal fibrosis and aortitis was the most prevalent presentation in both groups (2011 and 2019 criteria) with 38.5% and 28.6% respectively. <h3>Conclusion</h3> IgG4-RD is a recently described entity that is very heterogeneous in terms of its clinical, analytical and histopathological presentation. According to our series, clinical heterogeneity is the rule, being the retroperitoneal fibrosis and aortitis the most frequent. There are differences when we use the different criteria. ACR/EULAR 2019 classification criteria are stricter criteria that allows us to classify patients more accurately. In our series 6 patients fulfilled Umehara-Okazaki criteria but not ACR/EULAR due to giving more importance to histopathology, clinical manifestations and the need to reach a minimum score in which, for example, only IgG4 levels are not enough. Therefore, on many occasions, a multidisciplinary approach with experienced teams is necessary. <h3>References</h3> [1]Wallace ZS, Naden RP, Chari S, et al. The 2019 American College of Rheumatology/European League Against Rheumatism Classification Criteria for IgG4-Related Disease. <i>Arthritis Rheumatol</i>. 2020 Jan;72(1):7-19. [2]Umehara H, Okazaki K, Masaki Y, et al. Comprehensive diagnostic criteria for IgG4-related disease (IgG4-RD), 2011. Mod Rheumatol. 2012 Feb;22(1):21-30. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.